Many useful compositions are made of two components that are not normally mixed together until immediately prior to the time that a quantity of the composition is needed for use. For example, the components of epoxy-based adhesives are stored separately from each other, because once the components come into contact with each other a chemical reaction is initiated that eventually turns the mixed composition into a hardened mass. For that reason, epoxy-based adhesives are widely available in packages that include two compartments or two separate containers that keep the components of the adhesive initially isolated from each other.
In recent years, there has been increased interest in “single use” containers for compositions made of two components that are initially kept apart from each other. Such containers typically avoid the need to measure out separate quantities of each component before mixing. These containers also help assure that the components, when mixed, are present in the desired ratio of the resulting composition. Additionally, if the components are mixed together within the container, the need for a mixing well, pad, container or other type of mixing structure is avoided.
Single use containers for multiple component compositions are especially convenient for storing medical and dental compositions, because the container along with the applicator can be disposed of after use for a single patient. In this manner, the risk of transferring an infectious disease from one patient to another is substantially reduced.
Oftentimes, only a relatively small quantity of the composition is needed at any one time, and the smaller “single dose” or “single use” containers help ensure that a freshly-mixed batch of the composition is available when needed.
Reference is made to EP-A-0 895 943, EP-A-1 106 147, EP-A-1 576 934, U.S. Pat. No. 4,836,370, and U.S. Pat. No. 6,857,805 which generally relate to package assemblies.